NASA carried out a successful test on Thursday, August 18, of a rocket engine that could eventually power a manned Mars missions The seven-and-a-half minute test-fire of the RS-25 engine was part of a series of tests for a new deep space rocket program, the Space Launch System, according to NASA. The space agency will use four RS-25 engines to propel the Orion capsule into orbit with the first unmanned launch planned for 2018.